The objective of this contest is to see who can design, construct and test the most efficient bridge within the specifications. Model bridges are intended to be simplified versions of real-world bridges, which are designed to accept a load in any position and permit the load to travel across the entire bridge. In order to allow the contest to proceed in a reasonable amount of time only one loading position is actually tested.

1. Materials

a.  The bridge must be constructed using only pasta and Elmer’s White Glue. Not Elmer’s wood glue or other glues made by Elmer’s.

b.  No other materials may be used. The bridge may not be stained, painted or coated in any fashion with any foreign substance.

2. Construction

a.  There is a mass limit on the bridge of 600. grams. However a mass of bridge to mass held ratio will be used to determine the winner.

b.  The bridge (see Figure 1) must span a gap (G) of 30. cm, be no longer (L) than 40. cm, have a maximum width (W) of 8.0cm, be no taller (H) than 20. cm above the support surfaces. A box of these dimensions has been constructed. If your bridge does not fit within this box it does not meet specs (see section 5).

c.  No portion of the bridge shall extend below the top of the support surfaces.

d.  The loading plane (P) shall be horizontal and shall lie no more than 5.0 cm above the support surfaces. The bridge may extend above the loading plane as long as clearance is provided for the U-bolt, loading plate and U-bolt nuts (see section 3).

e.  The bridge must be constructed to provide for the loading plate (see section 3). Clearance for the U-bolt to hang vertically through the bridge will be provided by two 12.7mm (1/2inch) holes (loading points – Figure 1) 5.0 cm on each side of the center point (see Figure 3 for the full size view of the U-bolt) on the middle of the 30. cm gap. The completed bridge must be furnished with U-Bolt mounting holes prior to competition day.

3. Loading

a.  The load will be applied downward, from below, by means of a standard 3/8inch U-bolt (with 3-7/8” spacing between ends – shown full size in Figure 3) and its associated rectangular plate of thickness 2. mm with approximate dimensions of 121. mm x 19. mm (see Figure 2 and Figure 3 – full size) resting on the loading plane of the bridge. Masses will be supported on a vertical loading rod suspended from the U-bolt.

b.  The two edges of the loading plate will be parallel to the longitudinal axis of the bridge at the time of load application.

c.  The load will be applied on the longitudinal axis, as shown in the diagram (Figure 1), of the bridge with the loading plate centered on the 300. mm gap.

4. Testing

a.  The bridge will be centered on the support surfaces.

b.  The loading plate will be located on the bridge at the specified loading location and the load will be applied from below, as described in section 3 above.

c.  Competition loading will stop at 25.kg. However, loading will continue until bridge failure if there is time.

d.  Bridge failure is defined as the inability of the bridge to carry additional load, or a load deflection of 2.5cm under the loading location, whichever occurs first.

e.  The bridge with the highest structural efficiency, E, will be declared the winner.

E = Load supported in grams (25,000g maximum) / Mass of bridge in grams

5. Aesthetics

a.  The bridge may not be constructed as a solid block of pasta. The design must include some type of arch, truss, beam, or suspension structure designed to improve the structural integrity or efficiency of the bridge.

b.  Bridges that do not meet the aesthetic requirement may be deemed ineligible for testing or given a penalty of up to the equivalent point value of bridge disqualification at the instructors’ discretion.

6. Qualification and Grading

a.  Bridges that meet all of the above requirements and holds the entire 25 kg will receive a grade no lower than a 93%. The determination of the actual grade will be based on a ranking of efficiency as calculated above in part 4. The best qualifying bridge will receive a 100% and the lowest efficiency bridge that meets all qualifications and holds 25 kg on the day of testing will receive a 93%.

b.  Bridges that meet all of the above requirements and fail to hold the entire 25 kg will receive a grade between 92% and 77%. The determination of the actual grade will be based on a ranking of efficiency as calculated above in part 4. The most efficient bridge will receive a 92% and the lowest efficiency bridge will receive a 77%.

c.  All construction and material requirements will be checked prior to testing by the judges. Bridges that fail to meet these specifications at the conclusion of the allowable time for checking will receive a grade of 70%.

d.  Bridges that meet specifications but cannot hold the U-bolt and attached bucket will receive an automatic grade of 70%.

e.  If, during testing, a condition becomes apparent (i.e., use of ineligible materials, inability to support the loading plate, bridge optimized for a single loading point, etc.) which is a violation of the rules or prevents testing as described above in Section 4, that bridge shall be disqualified. If the disqualified bridge can accommodate loading, it may still be tested as stated above.

f.  Decisions of the judges are final; these rules may be revised as experience shows the need.

g.  This project will count as a single test grade, comprising both the written and testing portions.

7. Due Dates:

Tuesday, March 11, 2014 – The name of your partner, or none if you choose to work alone, and a list of at least four references you have found to help you design/build your bridge as well as a copy of the first page of the table of contents of your book, or the homepage of your website. If you will not be in school, you need to email this portion of the project to your teacher by 10 am that day. (One per group okay.)
(5% of Bridge Test Grade)

Monday, March 24, 2014 – Three page pre-testing paper. Page one – Cover sheet with you and your partner’s names, date, teacher(s), and period. Page two – One page write up detailing the reason for your design (Times New Roman, 12 pt font, 1 inch margin, double spaced). Page three - A picture of you, your partner, and your prototype under construction. As an alternative to page three you may bring in the bridge if you choose, however you must still complete pages one and two. If you will not be in school, you need to email this portion of the project to your teacher by 10 am that day. (One per group okay.) (15% of Bridge Test Grade)

Thursday, April 10, 2014 – Final bridges due. NO LATE projects will be accepted. If you will not be in school your project needs to get to school by 9 am that day.

Friday, April 11, 2014 – Bridge testing will be completed in class on this day.
(60% of Bridge Test Grade)

Thursday, April 24, 2014 – Two or three page post-testing paper. Page one – Cover sheet with your name, date, and period. Page two and possibly three – A write-up that answers but is not limited to the following questions:

-  Describe how your bridge failed.

-  What worked well for your bridge?

-  What would you change next time?

-  What did you learned from the project?

-  How does this satisfy the honors requirement?

The post-testing paper needs to follow the same format as the pre-testing paper (Times New Roman, 12 pt font, 1 inch margin, double spaced). If you will not be in school, you need to email this portion of the project to your teacher by 10 am that day. (Must be written individually; one per person.) (20% of Bridge Test Grade)

Figure 3- U Bolt

These instructions may be downloaded from your instructor’s class website. If you download and print this page of the instructions on a full sheet of 8.5” × 11” paper, it should come out actual size. (It will be smaller than actual size on the version handed out in class.)